A Single-Balanced Quadruple Subharmonical Mixer With a Compact if Extraction

A novel 21{35GHz single-balanced quadruple subhar- monic monolithic passive mixer is fabricated using the 0:15m GaAs pHEMT process. This mixer consists of a local oscillation (LO) spiral balun and a radio frequency (RF) band pass fllter which has an inter- mediate frequency (IF) extracted feature utilizing a pair of anti-parallel Schottky barrier diode to achieve quadruple subharmonic mixing mech- anism. The RF band pass fllter formed with an interdigital coupler and a low-pass network is used to reduce the chip dimension while oper- ating at a low frequency band and to improve the isolation between the RF and IF ports with a broadband operation. From the measured results, the mixer exhibits 11.3{15.1dB conversion loss, 28.8dB-high RF-to-IF isolation, 40dB-high LO-to-RF isolation, 60dB-high 3LO- to-RF isolation over a 21{35GHz RF bandwidth, and an input 1dB compression power of 4dBm. The compact IF extraction circuit sup- ports an IF frequency ranging from DC to 3.1GHz. The core chip size is only 0:67 £ 0:75mm 2 .